Solar control coatings having a layer stack of glass/Si3N4/NiCr/Si3N4 are known in the art, where the metallic NiCr layer is the sole infrared (IR) reflecting layer in the coating. In certain instances, the NiCr layer may be nitrided. For example, see U.S. Pat. No. 6,926,967, which is hereby incorporated herein by reference. See also U.S. Pat. No. 5,688,585.
Unfortunately, while such layer stacks with NiCr IR reflecting layers provide efficient solar control and are overall good coatings, they are lacking in terms of being able to achieve a wider palette of available colors when desired. For example, with such a coating stack, if bluish green is desired the approach is to significantly increase the bottom dielectric thickness which unfortunately results in undesirable interference effects in that particular coating.
Thus, in certain example non-limiting embodiments of this invention, it is desired to provide a layer stack for a coating that can achieve a broader range of color possibilities when desired, compared to the above-identified layer stack of glass/Si3N4/NiCr/Si3N4.
In certain example embodiments of this invention, it has surprisingly been found that by introducing a breaker layer into the bottom dielectric of the above-identified layer stack, such improvements can be achieved. In certain example embodiments of this invention, it has been found that the provision of a thin metallic, substantially metallic, or metal nitride breaker layer in the bottom dielectric of the above-identified coating provides for improved color control and/or ranges when desired, and also provides for good thermal stability (low ΔE* value(s)) if desired.
In certain example embodiments of this invention, heat treated (HT) coated articles have a glass side reflective ΔE* value due to heat treatment of no greater than 4.5, more preferably no greater than 4.0, even more preferably no greater than 3.5, and most preferably no greater than 3.0. For purposes of example, the heat treatment (HT) may be for at least about 5 minutes at a temperature(s) of at least about 580 degrees C., and is sufficient for thermal tempering. The term ΔE* is known in the art and is indicative of thermal stability upon heat treatment, and is defined and explained for example in U.S. Pat. No. 6,926,967 which is incorporated herein by reference.
Coated articles may be designed to achieve various desired glass side reflective coloration in different example embodiments of this invention, including but not limited to green, bronze, grey and/or blue glass side reflective coloration if desired.
Generally speaking, certain example embodiments of this invention fulfill one or more of the above listed needs by providing coated article including a layer system supported by a glass substrate, the layer system comprising: a first dielectric layer comprising silicon nitride; a first layer comprising NiCr on the glass substrate over at least the first layer comprising silicon nitride; a second dielectric layer comprising silicon nitride on the glass substrate over at least the first layer comprising silicon nitride and the first layer comprising NiCr; a second layer comprising NiCr on the glass substrate over at least the second dielectric layer; a third dielectric layer comprising silicon nitride on the glass substrate over at least the second layer comprising NiCr; and wherein the second layer comprising NiCr is at least twice as thick as the first layer comprising NiCr.
In certain other example embodiments of this invention, there is provided a coated article including a layer system supported by a glass substrate, the layer system comprising: a first dielectric layer; a first layer comprising NiCr and/or Nb on the glass substrate over at least the first dielectric layer; a second dielectric layer on the glass substrate over at least the first dielectric layer and the first layer comprising NiCr and/or Nb; a second layer comprising NiCr and/or Nb on the glass substrate over at least the second dielectric layer; a third dielectric layer on the glass substrate over at least the second layer comprising NiCr and/or Nb; and wherein the second dielectric layer is located directly between and contacting the first and second layers comprising NiCr and/or Nb. One or more of the dielectric layers may be of or include silicon nitride in example embodiments of this invention. One or both of the layers comprising NiCr and/or Nb may be of or include one or more of NiCr, NiCrNx, NbCr, NbCrNx, NbZr, NbZrNx, Nb and/or NbNx in certain example embodiments of this invention.